Clinical assessment of neurologic and sensory functions of the newborn infant require considerable experience, with results usually expressed in qualitative terms. For the past several years, we have investigated the way that certain reflexes can by modified by sensory signals that either accompany or precede the event that elicits the reflex and have confirmed the applicabilities in the newborn infant. In these studies, it a tone (reflex-modifying stimulus), which is itself too weak to elicit a measureable eyeblink response, is presented simultaneously with, or precedes, a mild tap to the glabella (reflex-eliciting event), it results simultaneously with or, precedes, a mild tap to the glabella (reflex- eliciting event), it results in an alteration of the eyeblink amplitude. Thus, by varying the characteristics of the tone and its temporal relationship to the tap, and by measuring the amplitude of the resulting eyeblink, the limits of several modifying effects of the auditory system can be objectively assessed and provide insight into the way in which the central nervous system processes acoustic signals. In order to establish the utility of reflex modification as an objective clinical tool indetecting abnormalities of sensory and neural dysfunction, it would be important to study the response of the neonate at risk and to compare the results of this technique to standard neurophysiologic tests of brainstem integrity. The research proposed here is designed to test infants exposed prenatally to cocaine with both reflex modification and auditory brainstem evoke responses, Infants screened for a positive history of maternal cocaine use will receive a simple reflex modification paradigm consisting of a sequence of eyeblink-eliciting taps to the forehead. The tap will be elicited by a miniature solenoid with a Teflon striker which delivers a mild controlled tap to the glabella. On half of these trails (randomly selected), a brief 90 dB SPL tone will accompany the tap. A photoreflective densitometer attached to a TDH 39 earphone provides an objective measure of eyeblink amplitude. Auditory brainstem testing will be performed using standard electrophysiologic procedures within a one week period of the reflex modification test. The data from these two procedures will allow assessment of sensory and neural deficits by noninvasive techniques and provide an objective measure that stimuli at some level are being processed, giving indication as to central nervous system function and organization. The significance of the findings in predicting later cognitive and/or neurologic sequelae can only be determined by long-term follow-up.